Felt driers for paper-making machinery



Dec. 27, 1966 J. A. MEANS 3,293,767

FELT DRIERS FOR PAPER-MAKING MACHINERY Filed March 24, 1964 INVENTOR. JOHN A. MEA NS Wil M a/gflj hi5 ATTORNEYS United States Patent York Filed Mar. 24, 1964, Ser. No. 354,314 12 Claims. (Cl. 34-9) This invention relates to felts for paper-making machinery and, more particularly, to felts treated in a novel and highly effective manner whereby, when they are used in paper-making machinery, for example to pick up and transport a wet paper web produced by a wet-end machine, they wet or work in quickly and have little tendency to entrap fines from the web. Felts treated in accordance with the invention may be used in any part of paper-making machinery where conventional felts may be used, but the new felts have greatest utility when used as pick-up felts in paper-making-machine press sections.

Conventional felts for use in, say, the press section of a paper-making machine are seriously deficient in two major respects: (1) they require a wetting or working in period of about four hours before becoming sufficiently wet to perform their intended function of picking up a wet paper web from the wet end of a paper-making machine and transporting the web through water-extraction means such as pressure nip and suction means in order to extract water from the web of paper, and (2) fines from the paper have a tendency to become permanently lodged in the felts on contact therewith. The suction usually employed to force air through the web of paper and thence through the felts in order to extract water from the web of paper rather quickly causes the fines to clog the interstices between the woven warp and filler strands of the felts, even though felt cleaners are mounted on the machine for cleaning the felts. These two deficiencies of conventional felts necessitate frequent felt changes and greatly increase the down time of paper-making machinery and therefore contribute substantially to the cost of paper manufacture.

An object of this invention is to remedy the deficiencies noted above. In particular, an object of the invention is to provide a felt for paper-making machinery which wets or works in much faster than conventional felts and which does not permanently entrap fines from a paper web transported by the felt but releases them readily in response to the passage of a cleaning fluid such as air through the felt as the felt traverses cleaning and dewatering apparatus.

These and other objects of the invention are attained by the provision of a paper-making-machine felt which has a finish imparting to the felt water and oil repellency.

An understanding of further aspects of the invention may be obtained from a consideration of the following detailed description of representative embodiments thereof and the accompanying drawing, in which the sole figure is a schematic elevation showing the mounting of paper-press felts treated in accordance with the invention in a paper-press section adjacent to the wet end of a paper-making machine.

The figure shows a wire 10, which may be a conventional forming wire of a wet-end machine, trained about a roll 11 and transporting a wet web 12 of newly-formed paper in the direction indicated by the arrow. The word paper is used in a generic sense to include paper, paperboard, and similar products. A roll 13 provided with suction means 14 removes the wet paper web from the wire 10, and the web 12 adheres to a pick-up felt 15 trained about the roll 13 and about guide and tension rolls 16.

The suction means 14 is stationary, and the circumference 20 of the roll 13 is perforated and rotatable about the axis 21 of the roll 13. Accordingly, the wet paper web 12 is transported on the felt 15 from the wire 10 to a first suction and pressure nip 22 formed by the roll 13 and a plain rotatable roll 23. The rolls 13 and 23 are made to rotate in the directions shown by the arrows. In traversing the circumference of the roll 13 between the wire 10 and the nip 22, the wet web 12 has water extracted therefrom by the passage of air into the web 12 and thence into the pick-up felt 15 and the circumference 20 of the roll 13. The suction and pressure nip 22 extracts additional water from the web 12 by a combination of suction and pressure.

As a given part of the circumference 20 of the roll 13 rotates beyond the suction means 14, centrifugal force causes the perforations in the circumference 20 to give up the water contained therein to a save-all 25 mounted adjacent to the roll surface 20 and on the opposite side of the roll 13 from the portion of the roll 13 about which the pick-up felt 15 and web 12 are trained.

Owing to the different surface characteristics of the roll 23 and the felt 15 and to the relative position of I the roll 23 with respect to the terminal end of the suction box 14, the web 12 is trainable around the roll 23. The web 12 is in fact so trained and passed through a suction and pressure nip 26 formed by the roll 23 and a roll 27 having a rotatable foraminous circumferential surface and a stationary suction-producing means 24 mounted therein for applying suction to the web 12 as it passes through the nip 26. The roll 27 is made to rotate in the direction shown by the arrow. A second press felt 28 is trained with the web 12 through the nip 26, where it facilitates the extraction of additional water from the web 12, and about tension and guide rolls 29. v

The web 12 adheres to the surface of the roll 23 to a point beyond the nip 22 and from that point is trained away from the roll 23 and about a guide roll 30 and onto a third press felt 31. The press felt 31 transports the web 12 through athird suction and pressure nip 32 formed by a roll 33 having a rotatable foraminous circumference and stationary suction means 34 therein and a rotatable plain roll 35. The rolls 33 and 35 are made to rotate in the directions shown by the arrows. third press felt 31 is also trained about guide and tension rolls 36.

The web 12 adheres to the circumference of the roll 35 to a point beyond the nip 32 and from that point is trained away from the roll 35 and about guide rolls 37,

38, and 39 and to apparatus such as a drying section (not. shown) for further processing.

The structure of the rolls and the arrangement of the rolls and felts shown herein are disclosed in my copending application Serial No. 28,114, filed May 10, 1960, and form no part of the present invention but are set forth for illustrative purposes. Obviously, any other suitable rolls and arrangements of rolls and felts may also be used in accordance with the present invention, which relates to felts treated in a novel and highly effective manner.

Materials which may be used in treating a paper-machine felt in, accordance with the invention include PC- 208; Zelan FF; the homopolymer of the acrylate ester of N-propyl, N-ethanol perfluorooctanesulfonamide-- C F SO N(C H CH CH OCOCH=CH a polymer of the acrylate ester of N-butyl, N-ethanol perfluorooctanesulfonamide- C F SO N(C H )CH CH OCOCH=CH The' a polymer of the methacrylate ester of N-ethyl, N-ethanol perfluorooctanesulfonamide- C F SO N(C H CH CH OCOC(CH )=CH a polymer of the methacrylate ester C3F17SO2N(C4H9) (CH OCOC(CH =CH a polymer of the acrylate ester-- C F SO N(C H (CH OCOCH=CH a polymer of the acrylate ester C F SO N(C H )CH CH OCOCH=CH a polymer of the acrylate ester- C F SO N(CH (CH OCOCH=CH the copolymer in 25:75 mole ratio of butadiene and the acrylate ester of N-ethyl, N-ethanol perfluorooctanesulfonamide a latex copolymer of a methacrylate ester monomer and butadiene in 70: 30 mole ratio, employing the methacrylate ester of N-ethyl, N-butanol perfluorooctanesulfonamide-- FC-208 is a trademark of Minnesota Mining and Manufacturing Co. for a substance believed to be a nonionic emulsion of a fluorocarbon resin, the resin being a polymer of a vinyl perfluoro acid ester, a polymer of a perfluoro ester of acrylic acid, or a copolymer of a vinyl perfluoro acid ester and a perfluoro ester of acrylic acid. See Herman B. Goldstein, Properties of Cotton Fabrics Treated With Fluorocarbon Combinations With Water- Repellents, Textile Research Journal, April 1961, page 378.

Zelan is a trademark of E. I. du Pont de Nemours & Co. for a substance believed to be composed, at least in part, of a long chain nitrogen complex, particularly a pyridene, and to combine with certain reactive groups of textile fibers. Cf. Handbook of Material Trade Names, by O. T. Zimmerman and Irvin Lavine, 1953 edition.

The other materials set forth above as examples of materials which are suited for use in accordance with the invention are disclosed in patents to Ahl-brecht et al., Nos. 2,803,615 and 2,841,573. Those patents also disclose methods of making the basic compounds, of polymerizing them, and of employing the materials to provide cloth with a finish imparting to the cloth water repellency and oil repellency.

Example I A 1% solids (by weight) aqueous solution of a fluorocarbon resin (FC-208) was prepared and placed in an open-top tub approximately 7 feet in diameter and of a depth approximately equal to the diameter. Approx-imately 2 gallons of the solution were used per pound of felt to be treated. The solution was heated to about 90 F. and a single thickness of an endless woven papermaking-machine felt comprising about 75% wool and 25% nylon was passed through a nip formed by a pair of rubber-covered wringer rolls mounted above the top of the tub, a loop of the felt dipping into the heated solution. The rolls were turned to run successive portions of the felt alternately through the nip and the heated solution for a period of about one hour. The felt was dried on a metal roll steam-heated to about 200 F.

The felt was then cured for five minutes in an oven at about 250 F., washed in a mild nonionic detergent solution at about 115 F., rinsed in water at about 115 F., and dried on a metal roll steam-heated to about 200 F. The treated felt was found to have increased in weight by about 1%.

In tests conducted on paper-making-machine press sections equipped with felts treated with the fluorocarbon resin, it was found that the felts had a wetting or working in time of approximately 30 minutes instead of the approximate four hours required for conventional felts. It was found, further, that the felts could be used many times longer than conventional felts before being discarded on account of clogging of the interstices between the woven warp and filler strands with fines. Machine down time and the cost of paper manufacture were therefore reduced.

Example II A 3% solids (by weight) aqueous solution of la pyridene compound (Zelan FF) was prepared and placed in the same open-top tub referred to in the previous ex-- ample. Approximately 2 gallons of the solution were used per pound of felt to be treated. The solution was heated to about 140 F. and a single thickness of an endless woven paper-making-mach-ine felt comprising about 75 wool and 25% nylon was passed through the nip referred to in the previous example, a loop of the felt dipping into the solution. The source of heat was removed from the solution so that the temperature of the solution dropped towards room temperature. Meanwhile, the rolls were turned to run successive portions of the felt alternately through the nip and the solution for a period of about one hour. The felt was dried on a metal rol'l steam-heated to about 200 F. The felt was then cured for five minutes in an oven at about 250 F Washed in a mild nonionic detergent solution at about F., rinsed in water at about 115 F, and dried on a metal roll steam-heated to about 200 F. The treated felt was found to have increased in weight by about 3%.

Felts treated in accordance with this example performed substantially the same as those treated in accordance with the previous example, Wetting or working in quickly and staying clean, soft, and open throughout their useful lives. They have been removed when worn out, but, throughout their useful lives, their performance has been uniformly good rather than changing and deteriorating in the manner of conventional felts, which receive only moth-proofing and similar treatment Example III The acrylate ester C F SO N(C H )CH CH OCOCH=CH is prepared and polymerized in the manner disclosed in Example I of the previously-mentioned Patent No. 2,803,615. A latex sizing solution is prepared in the manner disclosed in the example, the latex solids content of the solution being about 1%. A conventional papermaking-machine felt is dipped into the solution, passed between squeeze rolls to remove excess solution, and dried by heating at F. for 10 minutes. The treated felt, though water repellent and oil repellent when subjected to many conventional tests for Water repellency and oil repellency, surprisingly wets or works in when used, for example, as a pick-up felt in a paper-making machine, much more rapidly than a conventional felt and shows much more resistance than -a conventional felt to clogging with fines.

Example IV The vinyl ester c ia so rucn cH coocH=cH is prepared and polymerized in a manner similar to that described in Example I of the Patent No. 2,841,573 referred to above (see also Example II of the patent which incorporates Example I by reference). A conventional paper-making-machine felt is dipped into a 1% (by weight) solution of the polymer in xylene hexafluoride solvent, as disclosed in the patent, passed through squeeze rolls to remove excess saturant, and dried in an oven for minutes at 150 C. The treated felt, though water repellent and oil repellent when subjected to many conventional tests for water repellency and oil repellency, surprisingly wets or Works in, when used, for example, as a pick-up felt in a paper machine, much more rapidly than a conventional felt and shows much more resistance than a conventional felt to clogging with fines.

Thus there is provided in accordance with the invention novel and highly effective treated felts for use in papermaking machinery. The felts of the invention are particularly adapted for use as pick-up felts, where the web transported by the felt is wettest and most likely to deposit fines on the felt.

Many modifications of the representative embodiments of the invention disclosed above are possible within the spirit and scope of the invention. Accordingly, the invention is to be construed as extending to all the modifications thereof covered in the appended claims.

I claim:

1. In a method of extracting water from a Wet web of paper, the steps comprising transporting said web, by means including a paper-making-machine felt provided with a finish comprising a polymer of :a vinyl perfluoro acid ester and imparting to said felt oil and water repellency, into association with water-extraction means for extracting water from said web, at least a part of said water being transferred through said felt to said waterextraction means.

2. In a method of extracting water from a wet web of paper, the steps comprising transporting said web, by means including a paper-making-machine felt provided with a finish comprising a polymer of a perfluoro ester of acrylic acid and imparting to said felt oil and water repellency, into association with water-extraction means for extracting water from said web, at least a part of said water being transferred through said felt to said waterextraction means.

3. In a method of extracting Water from a wet web of paper, the steps comprising transporting said web, by means including a paper-making-machine felt provided with a finish comprising a copolymer of a vinyl perfluoro acid ester and a perfluoro ester of acrylic acid and imparting to said felt oil and water repellency, into association with water-extraction means for extracting water from said web, at least a part of said water being transferred through said felt to said water-extraction means.

4. In a method of extracting water from a wet web of paper, the steps comprising transporting said web, by means including a paper-making-machine felt provided with a finish comprising a pyiidene and imparting to said felt oil and water repellency, into association with waterextraction means for extracting water from said web, at least a part of said water being transferred through said felt to said water-extraction means.

5. In a method of extracting water from a wet web of paper, the steps comprising transporting said web, by means including a paper-making-machine felt provided with a finish comprising a solid flexible homopolymer of a compound selected from the class consisting of the acrylate esters and methacrylate esters of N-alkyl, N-alkanol perfluoroalkanesulfonamides which have in the molecule a perfluorocarbon tail, said acrylate esters having the formula 'R S0 N(R )RCH OC0CH=CH and said methacrylate esters having the formula R SO N(R )RCH OCOC(CH )=CH wherein R is a perfluoroalkyl group containing 4 to 12 carbon atoms, R is an alkylene bridging group containing 1 to 12 carbon atoms, and R is an alkyl side group containing 1 to 6 carbon atoms, said finish imparting to said felt oil and water repellency, into association with water-extraction means for extracting water from said web, at least a part of said water being transferred through said felt to said water-extraction means.

6. In a method of extracting water from a wet web of paper, the steps comprising transporting said web, by means including a paper-making-machine felt provided with a finish comprising a solid flexible homopolymer of the acrylate ester of N-propyl, N-ethanol perfluorooctanesulfonamide having the formula said 'finish imparting to said felt oil and water repellency, into association with water-extraction means for extracting water from said web, at least a part of said water being transferred through said felt to said water-extraction means.

7. In a method of extracting water from a wet web of paper, the steps comprising transporting said web, by means including a paper-making-machine felt provided with a finish comprising a solid flexible homopolymer of the acrylate ester of N-butyl, N-ethanol perfluorooctanesulfonamide having the formula said finish imparting to said felt water and oil repellency, into association with water-extraction means for extracting water from said web, at least a part of said water being transferred through said felt to said water-extractionmeans.

8. In a method of extracting water from a wet web of paper, the steps comprising transporting said web, by

means including a paper-making-machine felt provided With a finish comprising a solid polymer of fluorocarbon vinyl-type esters of the class consisting of vinyl esters and allyl esters of perfluoroalkanesulfonamido alkylenemoiiocarboxylic acids, said vinyl esters having the formu a and said allyl esters having the formula R SO N(R )ROOCH CH=CH wherein R; is a perfluoroalkyl group containing 4 to 12 carbon atoms, R is an alkylene bridging group containing 1 to 12 carbon atoms, and R is of the class consisting of a hydrogen atom and alkyl groups containing 1 to 6 carbon atoms, said finish imparting to said felt water and oil repellency, into association with water-extraction means for extracting water from said web, at least a part of said water being transferred through said felt to said water extraction means.

9. In combination, a paper-making machine formed with water-extraction means and a plurality of felt-training means and a felt trained over said felt-training means, said felt being adapted to carry a wet web of paper and being provided with a finish imparting to said fel-t water and oil repellency, said finish comprising a polymer of a vinyl perfluoro acid ester, and said water-extraction means being mounted to extract water from said web and transfer at least a part of said water through said felt.

10. In combination, a paper-making machine formed with water-extraction means and a plurality of felt-training means and a felt trained over said felt-training means, said felt being adapted to carry a wet web of paper and being provided with a finish imparting to said felt water and oil repellency, said finish comprising a polymer of a perfiuoro ester of acrylic acid ester, and said water-extraction means being mounted to extract water from said web and transfer at least a part of said water through said felt.

11. In combination, a paper-making machine formed with water-extraction means and a plurality of felt-training means and a felt trained over said felt-training means, said felt being adapted to carry a wet Web of paper and being provided with a finish imparting to said felt water and oil repellency, said finish comprising a copolymer of a vinyl perfluoro acid ester and a perfiuoro ester of acrylic acid, and said water-extraction means being mounted to extract water from said web and transfer at least a part of said water through said felt.

12. In combination, a paper-making machine formed with water-extraction means and a plurality of felt-training means and a felt trained over said felt-training means,

8 said felt being adapted to carry a wet web of paper and being provided with a finish imparting to said felt water and oil repellency, said finish comprising a pyridine, and said water-extraction means being mounted to extract water from said web and transfer at least a part of said Water through said felt.

References Cited by the Examiner UNITED STATES PATENTS 1,873,949 8/1932 Williams 34-1l6 2,537,129 1/1951 Goodwillie 34116 X 2,589,765 3/1952 Berglund ll7140 X 2,803,615 8/1957 Ahlbrecht et a1. 117l38.5 X 2,841,573 7/1958 Ahlbrecht et al. 117143 X 3,051,674 8/1962 Kress 117-140 X FREDERICK L. MATTESON, JR., Primary Examiner.

D. A. TAMBURRO, Assistant Examiner. 

1. IN A METHOD OF EXTRACTING WATER FROM A WET WEB OF PAPER, THE STEPS COMPRISING TRANSPORTING SAID WEB, BY MEANS INCLUDING A PAPER-MAKING-MACHINE LEFT PROVIDED WITH A FINISH COMPRISING A POLYMER OF A VINYL PERFLUORO ACID ESTER AND IMPARTING TO SAID FELT OIL AND WATER REPELLENCY, INTO ASSOCIATION WITH WATER-EXTRACTION MEANS FOR EXTRACTING WATER FROM SAID WEB, AT LEAST A PART OF SAID WATER BEING TRANSFERRED THROUGH SAID FELT TO SAID WATEREXTRACTION MEANS. 